<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>about us</title>
  <style>
    .bottm-line {
      position: relative;
    }
    .bottm-line::after {
      content: "";
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0%;
      height: 2px;
      background-color: #000;
      transition: width .3s cubic-bezier(.175,.885,.32,1.275), opacity .3s ease-in-out;
    }
    .bottm-line:hover::after {
      width: 100%;
    }
    .shopping {
      width: 100px;
      height: 50px;
      background-color: #e8e8e8;
    }

    @media (min-width:768px) {
      .media-sm {
        background-color: skyblue;
      }
    }

    @media (min-width:992px) {
      .media-md {
        background-color: yellow;
      }
    }
  </style>
</head>
<body>
  <div class="bottm-line shopping media-md media-sm"></div>
</body>
</html>